Thin film pattern layer battery systems

ABSTRACT

A battery assembly can be formed on a base layer provided on a substrate, with a thin film battery stack including an anode layer, a cathode layer, and an electrolyte layer between the anode and cathode layers. The thin film battery stack can be attached to a pattern film layer with holes for electrical connection to the anode and cathode layers.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application No. 61/801,013, filed Mar. 15, 2013,entitled “Thin Film Pattern Layer Battery Systems,” the entirety ofwhich is incorporated by reference as if fully recited herein.

TECHNICAL FIELD

The subject matter of this disclosure relates generally to batterysystems, and in particular to battery systems suitable for a range ofdifferent electronics applications including, but not limited to,computer systems, portable electronics and mobile devices. Morespecifically, the disclosure relates to battery systems and relatedmethods of manufacture, utilizing pattern layer techniques to provideimproved energy storage and performance.

BACKGROUND

Battery systems are utilized in a wide range of electronicsapplications, including computers, mobile devices, media players,personal digital assistants, power tools, navigational andcommunications equipment, and power storage and management systems forautomotive, rail, shipping and industry use. Depending on application,these systems are traditionally configured around a cellular anode andcathode battery structure, for example in a cylindrical rod-and-tubetype dry cell or flat plate flooded cell design. More advanced batterysystems may utilize a “Jelly roll” or “Swiss roll” configuration, inwhich the anode and cathode layers are provided on opposite sides of aflat sheet or flexible substrate, which can be rolled up folded inside abattery pouch or enclosure.

Battery system design is driven by a number of competing factors,including size, weight, energy capacity, storage density, cost, safety,reliability, durability, and ease of manufacture. In rechargeablebattery systems, thermal loading, recharge rate and other cyclingconsiderations may also be important concerns, particularly as theyrelate to service life and suitability for particular electronicsapplications. These design and engineering factors may also be weighteddifferently based on intended usage, for example as directed to largerscale battery systems for transportation and industrial power systems,as compared to smaller scale batteries for computers and consumerelectronic devices.

As a result, there is a continual need for improved battery systemdesigns, with increased service life and performance over a wide rangeof different operational configurations and demands. In particular,there is a need for improved thin film, laminar, and encapsulatedbattery technologies, with increased energy capacity and storage densitysuited to the ever-increasing service requirements of modern electronicsand power system environments.

SUMMARY

Exemplary embodiments of the disclosure include battery systems, methodsof making battery systems, and electronic devices utilizing batterysystems. The battery systems include anode and cathode layers having oneor more thin film pattern layer structures.

Representative processing methods may include forming a base layer on atemporary or process substrate layer, and forming a thin film batterystack on the base. The battery stack may include an anode layer, acathode layer, and an electrolyte layer between the anode and cathode.The battery stacks can also be laminated together with a patterned film,where the patterned film has pattern holes positioned for coupling toelectrodes or electrical power connectors.

Depending on application, the battery stack may be thermally processedon the process substrate in order to generate a phase transition in thecathode layer, for example a crystal phase transition. The thin filmbattery stack can then be transferred to a pattern layer or othersubstrate, which is not necessarily subject to the phase transitiontemperature.

The process substrate can be removed by an etching process stopped bythe base layer, for example using a silicon-based etch blocking layer.Alternatively, the base layer can also be removed, for example by laserablation or a mechanically process, or using an excimer laser togenerate a phase transition in the base layer, in order to release thebattery stack from the process substrate.

In stacked battery applications, a number of thin film battery cells arestacked for assembly into the battery system. For example, each stackmay include a cathode collector layer adjacent the cathode layer, andadjacent cells can be inverted so that the cathode collector layers areelectrically coupled within the battery assembly. Alternatively, barecathode or anode layers can be stacked adjacent to one another, and aconducting adhesive can be used to form the collector layers. Thebattery cells can also be encapsulated, for example using a polymer ororganic film.

In battery system applications, a number of thin film battery cells maybe arranged in a stacked configuration, where each of the cells includesan anode layer, a cathode layer, and an electrolyte layer between theanode and cathode layers. A patterned film can also be bonded to thebattery stack or multilayer cell structure, with pattern holespositioned for electrical connections to the anode and cathode layers,or the corresponding collectors.

The cathode layers may have a crystalline structure characterized by acrystalline phase transition temperature, and the thin film batterycells may be transferred to a target substrate material (e.g., afterprocessing), which is not necessarily thermally stable at thecrystalline phase transition temperature. The cells include anode andcathode collector layers, which can be positioned in an adjacent andelectrically coupled relationship within the stacked configuration.Alternatively, the bare cathode and anode layers may be coupledtogether, for example using a conducting bond to form the collector.Suitable encapsulants can be formed of organic liquid and polymermaterials.

These battery systems can be utilized in electronic devices, for examplea smartphone, tablet computer, or other mobile device. In theseapplications, a battery assembly is typically coupled to a controller,and configured to power a display. The assembly itself includes a numberof thin film battery cells arranged in a stacked configuration, whereeach of the thin film battery cells has an anode, cathode, andelectrolyte layer. The patterned film layer can be bonded to the thinfilm battery stack, with pattern holes positioned to provide electricalaccess to the anode and cathode structures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a battery system with improved thinfilm, laminar and/or encapsulation structures for increased energydensity, as described herein.

FIG. 1B is a perspective view of the battery system, with an alternateform factor.

FIG. 2 is a process flow diagram for making a battery system or batteryassembly, utilizing a temporary process substrate layer.

FIG. 3 is a process flow diagram for a battery system or assembly,utilizing an etched substrate and permanent base layer.

FIG. 4 is a process flow diagram for a battery system or assembly, in astacked cellular design.

FIG. 5 is a process flow diagram for a battery system or assembly, witha conducting adhesive collector layer.

FIG. 6 is a process flow diagram for a battery system or assembly, withmultiple cell encapsulation.

FIG. 7 is a process flow diagram for a battery system or assembly, withconducting adhesive anode and cathode collector layers.

FIG. 8 is a block diagram of a method for forming a battery system orassembly.

FIG. 9 is a schematic illustration of a representative electronic deviceincorporating a battery system or assembly.

DETAILED DESCRIPTION

This disclosure is directed to battery systems and assemblies forelectronic devices and power management systems. The batteries can beformed in a thin film transfer process, for example by forming a baselayer on temporary substrate, and forming a battery stack on the baselayer. The battery stack is processed on the temporary substrate, whichcan be relatively thick, and designed to withstand the high crystalphase transitions characteristic of lithium ion battery production.

Suitable thin film transfer processing techniques include, but are notlimited to, those described in METHOD FOR TRANSFERRING THIN FILM TOSUBSTRATE, U.S. Publication No. 2010/0066683, published Mar. 18, 2010,the entirety of which is incorporated by reference herein. Afterprocessing, the battery stack can be transferred to a more permanent andsubstantially thinner target substrate, increasing potential energydensity in the final battery assembly.

The target substrate does not require the same high-temperature thermalstability properties as the process substrate, providing for a muchwider range of possible materials. For example, a patterned filmsubstrate may be used, with pre-cut openings or pattern holes for accessto the anode and cathode collectors in the battery stack. The batterystacks can also be assembled into a multi-cell battery system, with orwithout permanent substrate layers. Depending on stacking configuration,the anode and cathode collectors layers may be eliminated, or replacedwith a conducting adhesive, decreasing the inactive mass and increasingpower and performance, within a given form factor or size and weightenvelope.

FIG. 1A is a perspective view of a battery (or battery system) 10 withimproved thin film, laminar and/or encapsulation structures. Thesestructures provide battery system 10 with increased energy density forimproved service life and performance, suitable for a range of differentelectronic and power system applications, as described herein.

As shown in FIG. 1A, battery system 10 is provided as a laminatedanode/cathode structure within enclosure 11, for example a batterypouch, casing or encapsulation layer. Protective film wrap 12 may beprovided over battery enclosure 11 to protect battery 10 during shippingand storage. Film wrap 12 can also include a label, barcode, or otherinformational indicia for inventory control, which is typically removedbefore insertion of battery system 10 into an electronic device.

One or more connectors 13 provide power, sensor and control connectionsto battery system 10, for example in a “pigtail” configuration with aconnector board or manifold 14 coupled to battery system 10 via flexcircuit 15. The flex circuit connection can be made through a side 16 orend 17 of battery enclosure 11, as shown in FIG. 1A, or a major surface18 (e.g., top or bottom surface) of enclosure 11. Flex circuit 15 alsoallows the connector board or manifold 14 to be relocated away frombattery enclosure 11 during installation and removal, and for wrappingand unwrapping of protective film 12.

Length L, width W and thickness T of enclosure 11 define the shape orform factor of battery 10, typically excluding protective wrapper 12 andany other components that are removed before installation. In theparticular configuration of FIG. 1A, for example, battery system 10 hasa substantially rectangular or oblong form factor, with width W definedbetween opposite sides 16 of enclosure 11, and length L defined betweenopposite ends 17. Thickness T is typically defined between the majorsurfaces of battery 10, for example between the bottom of batteryenclosure 11 and top surface 18.

FIG. 1B is alternate perspective view of battery system 10, with adifferent form factor. In this configuration, battery thickness T isrelatively greater, as compared to the thin-profile embodiment of FIG.1A, and as a fraction of battery length L and width W. This may providebattery system 10 with greater storage capacity, within a given areaL×W, in exchange for more weight and a larger volume envelope. Batterysystem 10 may also utilize a three-connector configuration, as shown inFIG. 1B, with control or sensor connector 13 and separate (e.g.,positive and negative) electrodes 19 for charging and power delivery.

Enclosure 11 is sometimes formed of a laminated pouch structure, forexample using a relatively thin or flexible metal such as aluminum orsteel, sandwiched between polymer protective layers or other coatings.Alternatively, enclosure 11 may be formed as a rigid case, using arelatively thicker metal or plastic material, or as an encapsulationlayer or encapsulated enclosure system, as described below. In advancedbattery systems, the internal structure (or battery core) of batterysystem 10 may be formed as a thin film or laminated anode/cathodestructure. In particular, a thin film lithium ion battery structure maybe utilized, in order to provide increased potential energy density anda higher power/weight ratio for battery system 10.

To achieve these advantages, the proportion of active battery materialsshould be increased or maximized, including lithium ion utilization inthe cathode layers, as compared to inactive materials and “overhead,”which should be decreased or minimized. To achieve high lithium ionutilization, particular crystalline structures or orientations may alsobe selected. For example, a substantially uniform or single-crystalstructure may provide greater energy density in the cathode layers, ascompared to a more amorphous structure. In addition, particular crystalplane orientations may be preferred, for example a (104), (101) or (012)crystal plane orientation, as compare to other possible orientations,such as (003).

In order to produce the desired crystal structures, the thin filmbattery layers are typically subjected to heating and other physical andchemical processes after deposition, in order to achieve the desiredphase transitions. For example, both the film battery layers and thesubstrate may be heated to relatively high temperatures of up to 700 Cor more, for extended periods of time, in order to achieve thermalcrystallization. Thus, the process substrate must be thermally,chemically and mechanically stable, even at high temperatures. Thisrequirement tends to limit the selection of suitable substratematerials, raising costs and reducing design options.

To address this problem, battery system 10 may utilize a thin filmtransfer process, in which the battery layers are deposited andprocessed on a temporary or process substrate material, then transferredto a new (permanent) substrate, or into a battery stack, after thedesired phase transformations have been achieved. This technique reducesthe more stringent process requirements on the permanent substratematerial, allowing for a wider range of design choices directed toperformance and cost effectiveness of the final battery system 10,rather the processing of individual battery stacks.

This approach also reduces or minimizes overhead and inactive materials.Flexible substrates, for example, are typically fabricated inroll-to-roll form, where each roll may be 1-2 meters wide, and up tothousands of meters long. In order to withstand typical jelly roll (andother standard battery) processing techniques, however, a minimumsubstrate thickness must be maintained. For example, up to 25 μm thicksubstrates may be utilized in display panel and touch screenapplications, while the typical active layer thicknesses may be as lowas 3-5 μm. Actual production parameters vary, but representative numberssuggest a potential material overhead of 500% or more, based on thesubstrate thickness, as compared to the active (e.g., cathode) layers.Thin film transfer techniques can be used to substantially reduce thisoverhead, increasing the active material fraction and correspondingpotential energy density, as described below.

FIG. 2 is a flow diagram illustrating a representative method or process20 for producing a battery stack 40, utilizing a thin film transfertechnique. Method 20 may utilize one or more steps including, but notlimited to, providing a temporary or process substrate (step 21),providing a sacrificial release or base layer on the process substrate(step 22), forming battery layers in a stack on the base layer (step23), processing the battery stack (step 24), attaching the battery stackto a transfer plate (step 25), releasing the process substrate (step26), transferring the battery stack to a permanent substrate (step 27),and removing the transfer plate (step 28). Process method 20 may thus beutilized to form one or more thin film battery stacks or cells 40 foruse a battery assembly such as battery system 10, above.

In step 21, process substrate or carrier layer 31 is provided in theform of a glass wafer or other suitable process substrate material 31.Generally, the composition and thickness of process substrate 31 areselected for thermal, chemical and mechanical stability and toleranceunder the potentially harsh battery processing conditions of processingmethod 20. In addition, the thickness of process substrate 31 is notsubstantially limited by overhead and inactive material considerations,because the battery stack is transferred from process substrate 31before final battery assembly, as described below.

In step 22, release or base layer 32 is provided on process substrate31. Base layer 32 may be formed, for example, of a silicon base or etchstopping material on which the battery layers are formed, and which isretained when process substrate 31 is removed. A seed layer or seedmaterial may also be provided, in order to encourage a particularcrystal plane orientation in an adjacent anode, cathode or collectorlayer, for example a lithium cobalt (LiCo) seed layer for forming alithium cobalt cathode or cathode collector with a selected crystalplane structure. Base layer 32 can also be provided as a sacrificiallayer, which is removed from the final battery assembly to releaseprocess substrate 31, or as a base layer, which is retained in the finalbattery assembly.

In step 23, laminar battery stack 40 is formed on base layer 32 andprocess substrate 31, for example using thin film deposition and maskingtechniques. In particular, battery stack 40 is formed of one or morebattery layers selected from the following: cathode current collectorlayers 33, cathode layers 34, electrolyte layers 35, anode layers 36,and anode collector layers 37.

Suitable anode and cathode layer materials include, but are not limitedto, lithium, lithium cobalt oxide, lithium iron phosphate and otherlithium metal phosphates, lithium manganese oxide, carbon, and graphite,or graphite infused with lithium ions. In one particular configuration,for example, anode layer 36 may be formed of lithium, and cathode layer34 may be formed of lithium cobalt oxide. Alternatively, anode layer 36may be formed of lithium cobalt oxide, or another lithium phosphate ormetal oxide material, and cathode layer 34 may be formed of graphite, orlithium ion infused graphite, or a lithium-based material.

Suitable materials for electrolyte layer 35 include, but are not limitedto, ethylene carbonate and diethyl carbonate containing lithium ioncomplexes, and other (e.g., acid or alkali) electrolytes having suitableion transport properties. In lithium ion applications of battery 10, theelectrolyte is typically non-aqueous, in order to avoid reacting withlithium metal components in the anode and cathode layers. A separatormaterial may also be provided in electrolyte layer 35, for example aporous or microporous ion transport material, a glassy or thin filmsolid electrolyte separator, or a paper, polymer, or fibrous compositemembrane material with selected ion transport properties. Suitableelectrolyte and separator materials also include, but are not limitedto, polyethylene lithium ion transport materials, lithium phosphate,lithium phosphorous, and lithium phosphorous oxynitride (LiPON orLiPOxNy) materials, polymer, carbon (e.g., carbon nanotube) andcomposite membrane materials, and lithium-salt type electrolytes in asubstantially solid polymer composite, for example in a lithium polymerbattery configuration.

The particular configuration of battery stack 40 is merelyrepresentative, and the number and order of the individual anode,electrolyte, cathode and collector layers 33-37 may vary. For example,the layers may be reversed or inverted with respect to base layer 32 andprocess substrate 31, and collector layers 33 and 37 may be providedeither as separate metal or conduction layers, or combined with theanode and cathode layers. Depending on the charging or dischargingstate, moreover, the charge flow in anode and cathode layers 36 and 34may be reversed, and these designations may be modified accordingly,without loss of generality.

In step 24, battery stack 40 is processed to obtain selected materialproperties. For example, battery stack 40 may be heat treated to obtaincrystallization or another phase change in cathode layer 34, or in otherlayers of battery stack 40. Generally, the crystallization temperaturemay be relatively high, for example up to 700 C or more. In applicationswhere a seed layer or seed material is provided, the crystallizationtemperature may be somewhat lower, for example about 400 C. or above. Inadditional examples, the relevant phase change temperature varies,depending upon the desired properties of battery stack 40, and thecorresponding material composition and configuration of battery layers31-37.

Processing step 24 may also include encapsulation of battery stack 40within encapsulation layer 38. Encapsulation layer 38 provides arelatively thin, electrically insulating, chemical and mechanicalbarrier for battery stack 40, protecting from environmental effectsincluding electrical contact, mechanical stress, and moisture intrusion.

Encapsulation layer 38 may be provided before or after heating and otherprocessing steps on battery stack 40. For example, suitable materialsfor encapsulation layer 38 include ceramics and other high temperatureor refractory materials, which may be applied before or after thermalcrystallization of cathode layers 34 (or anode layers 36). Additionalsuitable materials include polymer coatings and epoxy resins, for whichthe application sequence may depend upon the processing temperature andheating time, as compared to the thermal stability of the encapsulatingmaterial.

In transfer step 25, battery stack 40 is bonded to a transfer plate ortransfer layer 41, for example using an easy release adhesive or otherreleasable bonding material 39. Suitable materials for transfer layer 41include, but are not limited to, flexible polymer materials such aspolyethylene terephthalate (PET) and other flexible polymers, and rigidmaterials such as glass, and silicon wafer materials. Suitable materialsfor adhesive or bonding material 39 include soluble glues and adhesive,which can be selected to temporarily adhere battery stack 40 to transferlayer 41, and which can later be dissolved or otherwise removed.

In release step 26, process substrate 31 is removed or released andbattery stack 40 is transferred to transfer layer 41. Depending uponapplication, base layer 32 may also be removed, for example when using asacrificial release material. Alternatively, base layer 32 can also beretained in the final battery assembly. For example, a chemical etchingprocess may be utilized, which is stopped by base layer 32 as formedwith an etch-resistant material, such as silicon. Alternatively, asacrificial base or release layer 32 may be used, which undergoes aphase change when subject to an additional processing step, for exampleusing an XeCl excimer laser or other radiation source to crystallize anamorphous silicon base layer 32. Base layer 32 can also be ablated, orvaporized in an annealing process or other heat treatment. Depending onremoval technique, moreover, process substrate layer 31 may either bedestroyed, or preserved for reuse in a subsequent processing method 20.

In step 27, battery stack 40 is attached to the target or permanent(intended) substrate 42, for example using an adhesive layer 43laminated between the bottom of battery stack 40 (e.g., cathodecollector layer 33, and/or other battery layers), and target substrate42. Suitable materials for adhesive layer 43 include, but are notlimited to, permanent adhesives such as thermosetting adhesives, epoxyadhesives, and radiation-cured adhesive materials, and other bondingagents. In additional applications, target substrate 42 may be providedin the form of a patterned film, which can be laminated onto batterystack 40, or onto a thin film stackup including multiple battery cells40. Thin film type target substrates 42 can be precut or patterned withpattern holes or apertures P, in order to provide access to anode andcathode collector layers 37 and 33, as shown in step 28, and in order tomake power connections between the battery stacks and the assembledbattery system 10.

In step 28, transfer plate (or layer) 41 is removed, for example bydissolving or otherwise removing temporary adhesive layer 39. Aftercompletion of processing method 20, battery stack 40 is released fromprocess substrate 31 (and transfer layer or plate 41), and battery stack40 can be bonded to permanent or target substrate 42. One or moreindividual battery stacks 40 may then be utilized in a battery system10, for example in a stacked arrangement inside a battery enclosure 11,as shown in FIGS. 1A and 1B. Alternatively, the battery enclosure mayincorporate an encapsulation layer 38 and the target substrate 42, forexample in an encapsulated patterned film embodiment, or as describedbelow.

Based on the particular processing steps of method 20, target substrate42 is not subject to the same (e.g., high temperature and/or harshchemical) processing steps as battery stack 40, and target substrate 42does not necessarily require the same chemical, mechanical, and thermalstability properties as process substrate 31. Thus, target substrate 42may be formed from a wider range of materials that are selected forperformance within a particular battery system 10, independent of theprocessing steps utilized to produce battery stack 40. In particular,suitable materials for target substrate 42 may include plastics andother polymers, as well as various metals as well as higher temperatureglass and ceramic or refractory materials.

In addition, the thickness of target substrate 42 may also be selectedbased on battery performance considerations, rather than the processingrequirements of battery stack 40. Thus, target substrate 42 may besubstantially thinner than a typical battery substrate, forsubstantially less than 25 μm, as described above for more traditionalbattery designs. Depending on application, the thickness of targetsubstrate 42 may also be less than about 20 μm, for example about 10-20μm, or less than about 10 μm, for example about 5-10 μm.

This reduced thickness for target substrate 42 results in a batterysystem 10 with substantially more active material, as a fraction oftotal battery height, and provides a corresponding increase in potentialenergy density and storage capacity, as compared to other batterysystems with similar overall dimensions, but larger substratethicknesses. In very thin substrate applications, moreover, thethickness of target substrate 42 may be even less, for example about 5μm or less, or about 2-3 μm, providing a further increase in batterycapacity and performance.

FIG. 3 is a process flow diagram illustrating method 20 for producingbattery stack 40, in an alternate technique with a permanent base layer32. In this example, processing steps 21, 22, 23, 24, and 25 may besimilar to those of FIG. 2, above, or other thin film techniques may beused, as known in the art. In step 26, process substrate 31 is releasedor removed, for example by etching, and base layer 32 is retained as apermanent base layer for battery stack 40.

In this example, base layer 32 may be provided in the form of a siliconetch block or base layer, as described above, with or without a seedlayer for generating a particular crystal plane orientation in one ormore thin film battery layers 33-37. After processing battery stack 40to provide the desired crystalline structure and other materialproperties, process substrate layer 31 can be etched away, leaving thinfilm battery stack attached to base layer 32. Alternatively, amechanical process such as grinding can be used, avoiding the harshchemical environment typically associated with etching.

In step 27, battery stack 40 is attached to target substrate 42, forexample using a layer of permanent adhesive 43 to bond base layer 32 totarget substrate 42. In step 28, temporary adhesive 39 and transferlayer 41 are removed, preparing battery stack 40 for use in a batterysystem 10, as described above.

FIG. 4 is a process flow diagram illustrating method 20 for processing aplurality of battery stacks 40, in a multiple stacked cell design. Inthis example, processing steps 21-25 may also be similar to thosedescribed above, with base layer 32 provided in the form of asacrificial release layer, which is removed along with process substratelayer 31 in release step 26. Instead of bonding battery stack 40directly to a target substrate, however, a number of battery stacks 40are assemble into a multi-cell stack configuration, as shown in step 29.

Adjacent battery stacks 40 may also be inverted with respect to oneanother, with a layer of conducting adhesive 44 provided betweenadjacent cathode layers 34 or cathode collectors 33 (or both), forming asingle cathode connector 33 for two adjacent battery stacks 40.Alternatively, a non-conducting adhesive may be used, with separate(e.g. parallel) electrical connections between individual cathodecollector layers 33.

The order of individual thin film battery layers 33-37 can also bereversed or otherwise modified in individual battery stacks 40, so thatconducting adhesive 44 (or an insulating bonding agent) is providedbetween adjacent anode layers 36 and/or anode collectors 37. A varietyof different electrode couplings are also contemplated, for example withanode collectors 37 and cathode collectors 33 exiting from oppositessides of the stacked battery cell assembly, with additional conductiveadhesive 44 between adjacent portions of the respective collectorlayers.

In step 30, temporary adhesive 39 and transfer layers 41 are removed(see step 28, above), and stacked battery cells 40 are provided for usein a battery system 10. Additional battery stacks or cells 40 may alsobe added, to provide a multi-cell stacked battery design with anarbitrary number of battery stacks 40. One or more substrate layers 42and encapsulation layers 38 may also be included at the top or bottom ofthe individual battery cell stacks 40, or eliminated altogether,depending upon the desired chemical and mechanical properties of batterysystem 10.

FIG. 5 is a process flow diagram illustrating method 20 for processingmultiple layered battery stacks or cells 40, with a conducting adhesivecathode collector layer 33. In this example, no separate cathodecollector layer is formed in battery stack 40 (step 23), and bothprocess substrate 31 and base (or release) layer 32 are removed (step26), before bonding adjacent (inverted) battery stacks 40 (step 29).

Thus, conductive adhesive 44 is provided directly between adjacentcathode layers 34, and serves as both a bonding layer and a cathodecurrent collector, as shown in step 28. This design eliminates the needfor conventional separate or distinct cathode collector layers, reducingbattery height (or z-height) without removing active materials, andfurther increasing the potential energy density, with respect to otherdesigns.

FIG. 6 is a process flow diagram illustrating method 20 for processingbattery stacks or cells 40, with multiple cell encapsulation. In thisexample, a sacrificial base or release layer 32 is utilized (step 22),and there is no encapsulation layer in either thin-film deposition (step23) or subsequent processing of battery stack 40 (step 24). Depending onapplication, a separate cathode collector layer 33 may also be avoided,as described above with respect to FIG. 5. Using a suitable conductingadhesive layer 44 to form cathode collector 33 when adjacent batterystacks 40 are bonded together (step 29).

In stacking step 30, the top or bottom transfer layers 41 are removedand pairs of adjacent battery stacks or cells 40 are bonded along thecathode collector interfaces, for example with additional conductingadhesive 44 between adjacent cathode collectors 37. Alternatively, theindividual cell stacking order can be reversed, as described above, andadditional temporary adhesive 39 and transfer layers 41 may also beremoved, in order to stack an arbitrary number of battery cells 40. Themultiply stacked cells 40 can then either be enclosed in a traditionalbattery casing, or encapsulated as a unit, as described below.

In some designs, all the cathode collector layers 33 in a particularbattery system or assembly 10 are connected in parallel, as are theanode collector layers 37. Alternatively, individual battery stacks 40(or pairs or stacks of cells 40) may have a reversed orientation, inorder to provide one or more series couplings for higher output voltage.Thus, a wide range of different stacking configurations are encompassed,including different vertical layer ordering, and different horizontal(left and right) anode and cathode collector orientations, as long asshorts and other direct couplings across the anode and cathode layersare avoided in individual battery cells or stacks 40.

FIG. 7 is a process flow diagram illustrating method 20 for processingbattery stacks 40, with conducting adhesive anode and cathode collectorlayers. In this example, no separate cathode collector or anodecollector layers 33 and 37 are formed in deposition step 23, and bothprocess substrate 31 and sacrificial base layer 32 are removed inrelease step 25, before bonding adjacent battery stacks 40 (step 29).

In stacking step 30, pairs of adjacent battery stacks or cells 40 may bebonded together, as described above with respect to the example of FIG.6. As shown in FIG. 7, however, there are no separate anode collectorstructures, and conducting adhesive 44 serves as both the cathodecollector 33 and the anode collector 37. This provides a furtherdecrease in the stacking height of the battery assembly, with anadditional increase in power capacity and potential energy density, ascompared to a more traditional design with the same form factor, or withthe same mass and size envelope.

As shown in FIGS. 2-7, film transfer processing methods providesubstantial advantages in the manufacture and structure of individualbattery stacks 40, and for assembled multi-cell or multi-stack batterysystems 10. In particular, where current technology requires hightemperature anneal and crystallization process steps, few processingsubstrate materials are suitable, and these processing substrates do notnecessarily provide commensurate performance advantages in any givenbattery system 10.

The use of a temporary process substrate 31 decouples a number of theseprocessing concerns from the final battery assembly, allowing forthinner target (permanent) substrates to be utilized, or even none atall, depending upon final stacking configuration. This substantiallyreduces the inactive material in battery system 10, and increases thepotential energy density. In one particular set of applications, forexample, a processing substrate with a thickness of 25 μm or more can bereplaced with a target substrate with a thickness of 5 μm or less, forexample 2-3 μm, yielding a substantial reduction in inactive mass, and asubstantial increase in corresponding potential energy density and powercapacity. Alternatively, the z-height of the battery system can bereduced, within a given area, while maintaining or even increase totalpower output and storage capacity.

FIG. 8 is a block diagram of method 70 for forming a battery assembly,for example battery system 10 with one or more individual battery stacksor cells 40, as described above. Method 70 may include one or more stepsincluding, but not limited to, forming a base layer (step 71), forming athin film battery stack on the base layer (step 72), processing thebattery stack to achieve desired physical properties, and assembling thethin film battery stack into a battery system (step 80). Method 70 mayalso include one or more intermediate processing steps 74-79 andadditional assembly steps 81-83, as described below.

Forming a base layer (step 71) and forming a thin film battery stack onthe base layer (step 72), and other steps of method 70, may be performedaccording to any of the different examples of processing method 20, asdescribed above with respect to FIGS. 2-7, or using other thin filmprocessing steps known in the art. For example, the battery stack maycomprise anode, cathode, and electrolyte layers with or without distinctcollector layers, and the base layer may be formed on a temporaryprocess substrate or a permanent substrate material, such as a patternfilm substrate.

After the battery layers are deposited, the battery stack (or stacks)can be processed (step 73) to generate a crystalline structure in theanode or cathode layers, or other desired property, for example bythermal treatment or annealing. Additional chemical, thin film, andmechanical processes may also be applied, including encapsulation of theindividual battery stacks or cells.

Depending on embodiment, the thin film battery stack may be bonded to atransfer layer (step 74), for transfer from the process substrate (step75). The process substrate can be remove by etching, or by generating aphase transition in the base layer, in order to release the processsubstrate from the battery stack. The base layer can either be removedalong with the process substrate, or kept together with the batterystack, for assembly into the completed battery system.

The battery stack is typically transferred to the transfer layer forbonding to a target or permanent substrate (step 76), or for assemblyinto a multi-cell stack (step 77). Generally, the permanent targetsubstrate materials are retained with the battery stack, in the finalassembly, but a permanent substrate is not required. Any remainingtransfer layers can also be removed (step 78), either during thestacking process (step 77), or during final assembly of the batterysystem (step 80). A pattern film lamination can also be applied (step79), as described above.

In some examples, the thin film battery cells are stackedbottom-to-bottom, with a pair of cathode collectors placed in anadjacent and electrically coupled relationship. Alternatively, one ormore collector layers may be omitted, and the bare cathode layersthemselves may be adjacent. In this technique, a bond can be formedbetween adjacent pair of cathode layers, for example using a conductingadhesive, which forms a (single) cathode collector for the two adjacentcathode layers.

Similarly, battery cells can also be stacked top-to-top, or with areversed layer structure, so that the anode collector (or bare anode)layers are adjacent. A conducting bond can be formed between theadjacent collector layers, or between adjacent bare anode layers. Thus,the conducting bonds can be formed with a direct electrical connectionbetween adjacent anode or cathode layers, with no other interveningcollector layers.

Assembling the battery system (step 80) may include encapsulating thebattery stack (step 81), inserting the battery stack into a pouch orcasing (step 82), or both. Typically, the battery assemblies alsoprovides additional features, for example electrodes or otherconnectors, which are configured for connecting the battery stack (ormultilayer stack of cells) to an electronic device (step 83), asdescribed below.

The battery stacks can either be individually encapsulated (step 81), orencapsulated as a multilayer stack. For example, a multilayerencapsulation system may be provided to form a substantially continuousbarrier, surrounding the stack of individual thin film battery cells.

The battery stack (or stacks) can also be laminated together with apatterned film (step 79). The patterned film may include precut orpatterned openings for accessing the connector, for example as describedabove with respect to FIG. 2, in order to make power connections to theelectronic device.

FIG. 9 is a block diagram illustrating representative electronic device100, for example with housing 102 and controller 104 coupled to batterysystem 10, in order to provide power management and operational controlof device 100. In some applications, electronic device 100 is configuredfor use as a smartphone, tablet computer, or other mobile device.Alternatively, device 100 may be configured as a media player, digitalassistant, game player, personal computer or computer display; a laptop,desktop, notebook, or handheld computer; a navigational orcommunications system; a power tool or other power equipment; or a powermanagement component for use in a commercial, industrial, ortransportation power system.

Housing 102 is provided to protect the internal components of device100, and may be formed of a durable material such as aluminum and steel,or from metal, plastic, glass, ceramic, and composite materials, andcombinations thereof. Cover glass 106 is typically formed of a glass ortransparent ceramic material, for example silica glass or sapphire, or aclear plastic polymer such as acrylic or polycarbonate. In mobile deviceapplications, cover glass 106 may include a display window for a touchscreen, graphical interface or other display component 108.

Device 100 may also include a number of additional components powered bybattery system 10, including, but not limited to, a motion sensor andother internal accessories 110, audiovisual and sensor features 112including speakers, microphones, cameras, and lighting/indicatorfeatures (e.g., a light emitting diode or flash device), and variouscontrol devices 114, such as home, menu and hold buttons, volumecontrols, and other control elements, arranged variously with respect tohousing 102 and cover glass 106.

As shown in FIG. 9, controller 104 is coupled in signal and powercommunication with battery system 10, and one or more of display 108,internal accessories 110, audiovisual features 112, and control devices114. Controller 104 includes microprocessor and memory componentsconfigured to execute a combination of operating system and applicationfirmware and software, in order to provide power management and devicefunctionality including, but not limited to, data display, voicecommunications, voice control, media playback and development, internetaccess, email, messaging, gaming, security, navigation, transactions,and personal assistant functions. Controller 104 may also includeadditional input/output (I/O) components configured to supporthard-wired, wireless, audio, visual, infrared (IR), and radio frequency(RF) connections 116, for one or more external accessories 118, hostdevices 120 and networks 122.

While this invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes can be made and equivalents may be substituted forelements thereof, without departing from the spirit and scope of theinvention. In addition, modifications may be made to adapt the teachingsof the invention to particular situations and materials, withoutdeparting from the essential scope thereof. Thus, the invention is notlimited to the particular examples that are disclosed herein, butencompasses all embodiments falling within the scope of the appendedclaims.

We claim:
 1. An assembly method comprising: forming a base layer on aprocess substrate; forming a thin film battery stack on the base layer,the thin film battery stack comprising at least an anode layer, acathode layer, a cathode current collector layer, an anode currentcollector layer, and an electrolyte layer between the anode layer andthe cathode layer; and attaching the thin film battery stack to apatterned layer having pattern holes configured for electrical powerconnection to the thin film battery stack, the patterned holesincluding: a first pattern hole that physically exposes the cathodecurrent collector layer; and a second pattern hole that physicallyexposes the anode current collector layer.
 2. The method of claim 1,further comprising bonding the thin film battery stack to a transferlayer and transferring the thin film battery stack from the processsubstrate to the patterned layer.
 3. The method of claim 1, furthercomprising stacking a plurality of thin film battery cells for assemblyinto a battery system, each of the thin film battery cells comprising aninstance of the thin film battery stack.
 4. The method of claim 3,wherein the cathode current collector layer is adjacent the cathodelayer and wherein stacking the plurality of thin film battery cellscomprises stacking at least a pair of the cathode current collectorlayers in an adjacent and electrically coupled relationship within thebattery system.
 5. The method of claim 3, wherein stacking the pluralityof thin film battery cells comprises stacking at least a pair of thecathode layers in an adjacent and electrically coupled relationshipwithin the battery system.
 6. The method of claim 5, further comprisingforming the cathode current collector layer as an electricallyconducting bond between the adjacent pair of cathode layers.
 7. Themethod of claim 3, wherein stacking the plurality of thin film batterycells comprises stacking at least a pair of the anode layers in anadjacent and electrically coupled relationship within the batterysystem, and further forming the anode collector layer as an electricallyconductive bond between the adjacent pair of anode layers.
 8. The methodof claim 3, further comprising encapsulating the plurality of thin filmbattery cells on the patterned layer.
 9. The method of claim 1, furthercomprising precutting the pattern holes in the pattern layer prior toattaching to the thin film battery stack.
 10. The method of claim 1,wherein the first pattern hole and the second pattern hole are locatedat opposite sides of the patterned layer.
 11. The method of claim 1,wherein a majority of the patterned layer separates the first patternedhole from the second pattern hole.
 12. A method of assembling a batterycomprising: forming a first aperture and a second aperture in a patternfilm; forming a thin film battery stack on a substrate, the thin filmbattery stack including a cathode current collector layer an anodecurrent collector layer; and attaching the thin film battery stack tothe pattern film such that the first aperture physically exposes thecathode current collector layer and the second aperture physicallyexposes the anode current collector layer to allow for electrical powerconnection to the thin film battery stack.
 13. The method of claim 12,further comprising removing the substrate.
 14. The method of claim 13,wherein the substrate is larger than the pattern film.
 15. The method ofclaim 13, further comprising forming an additional thin film batterystack on the substrate after the substrate is removed from the thin filmbattery stack.
 16. The method of claim 13, wherein the operation ofremoving the substrate comprises chemically etching the substrate. 17.The method of claim 12, wherein the pattern film has a lower thermalstability than the substrate.
 18. The method of claim 12, wherein theoperation of attaching the thin film battery stack to the pattern filmcomprises attaching the thin film battery stack to the pattern filmusing adhesive.
 19. The method of claim 12, wherein the substratecomprises a glass wafer.
 20. The method of claim 12, wherein theoperation of attaching the thin film battery stack to the pattern filmcomprises laminating the pattern film onto the thin film battery stack.